1. Field of the Invention
The invention relates to a pixel unit and a liquid crystal display having the pixel unit, and particularly to a pixel unit having different regions that correspond to their respective V-T characteristic curves.
2. Description of the Related Art
FIG. 1 shows an equivalent circuit diagram for a pixel unit of a transflective LCD having a single cell gap. Each pixel unit has a reflective region Re and a transmissive region Tr, and light propagates through the reflective region Re achieves a phase difference that is about twice as the phase difference achieved by the light propagating through the transmissive region Tr. Hence, as shown in FIG. 1, the reflective region Re and the transmissive region Tr are respectively corrected by reflectance and transmittance gamma curves by means of two thin film transistors T1 and T2 to allow for competent optical matching.
FIG. 2 shows a schematic diagram illustrating drive architecture for the transflective LCD shown in FIG. 1. Referring to FIG. 2, the drive architecture 100 includes a thin film transistor array 102, a first image signal drive circuit 104, a second image signal drive circuit 106, and a scan signal drive circuit 108. Referring to both FIG. 1 and FIG. 2, the scan signal drive circuit 108 that generates scan signals is coupled to the gate of each thin film transistor through row electrodes G1A-G4A. The first image signal drive circuit 104 sequentially generates image signals that correspond to each scan signal, and the image signals are transmitted to the reflective region Re through column electrodes D1A-D4A and the thin film transistor corresponding to the reflective region Re (such as thin film transistor T1). The second image signal drive circuit 106 sequentially generates image signals that correspond to each scan signal, and the image signals are transmitted to the transmissive region Tr through column electrodes D1B-D4B and the thin film transistor corresponding to the transmissive region Tr (such as thin film transistor T2).
Though, in the above design, two thin film transistors T1 and T2 respectively control the reflective region Re and the transmissive region Tr to allow for competent optical matching in a single-cell-gap LCD, it requires complicated circuitry to implement the correction for gamma curves. For example, two image signal drive circuits and double column electrodes are needed as shown in FIG. 2. This considerably increases the fabrication cost and design complexity.